1、AEROSPACESTANDARDAS13003Issued 2015-02Measurement Systems Analysis Requirementsfor the Aero Engine Supply ChainRATIONALEThe aerospace industry is heavily reliant on inspection to ensure that parts and assemblies delivered to the purchaser meet drawing requirements. There are many differing requireme
2、nts across the aero engine supply chain, therefore, this standard is intended to harmonize these requirements into a single approach.The determination of what needs to be inspected is covered in a separate standard AS13002.This standard defines the essential requirements to establish acceptable meas
3、urement systems (for variable and attribute features) for use on aero engine parts and assemblies.TABLE OF CONTENTS1. SCOPE 31.1 Purpose. 32. REFERENCES 32.1 Applicable Documents 32.2 Definitions 43. APPLICABILITY 54. OVERVIEW OF MEASUREMENT SYSTEMS ANALYSIS (MSA) 55. ORGANISATION AND COMPETENCE REQ
4、UIREMENTS . 76. QUALITY SYSTEM . 77. MEASUREMENT SYSTEMS ANALYSIS REQUIREMENTS 77.1 Pre-Requisites. 77.2 Considerations when Planning a MSA Study 87.3 MSA Minimum Requirements . 118. ELEMENTS TO CONSIDER WHEN CONDUCTING MSA 128.1 MSA Design Factors . 128.1.1 Sample Selection 128.1.2 Sample Numbers 1
5、28.1.3 Operators 138.1.4 Low Sample Sizes. 138.1.5 In Part Variation. 13_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability
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9、NAL AS13003 Page 2 of 458.2 Analysis of Results 14 8.2.1 Gauge Resolution 14 8.2.2 Accuracy Ratio 14 8.2.3 Repeatability 14 8.2.4 Gauge Repeatability and Reproducibility (GR or which may prevent or seriously affect the satisfactory operation or functioning of the product. Specific Purchaser Feature
10、Classifications may exist.GAUGE REPEATABILITY e.g., gauge, operator, environment, fixture, etc. REPRODUCIBILITY: The ability of the measurement system to give the same result when elements of the system, such as operator or environment, are changed.RESOLUTION: The ability of the gauge to detect chan
11、ges in the characteristic being measured and discriminate between measurement values. STABILITY: A measure of how variation changes over time. This can be classified as short term or long term stability depending on the time frame involved.SUPPLIER: A supplier is any manufacturer of systems, sub-sys
12、tems, assemblies, components and materials for use within the Aero Engine Supply Chain.VARIABLE: Something that is liable to change and is not a fixed value. There may be one or more causes of the variation either acting independently or together. Variable or continuous data may take on any value wi
13、thin a finite or infinite interval depending on the resolution of the measurement system used to capture that value.3. APPLICABILITYThis standard is intended for businesses that design and/or manufacture products throughout the Aero Engine Supply Chain. The minimum requirements for both variable and
14、 attribute measurement systems are defined where used to validate product in its final condition.It is expected that these requirements shall be flowed down to all sub tiers within the supply chain and included within theirQuality Management System.Any additions or exclusions to this standard must b
15、e agreed with the purchaser.The scope of application of these requirements shall be defined by the purchaser, and this may include part numbers, processes, etc.4. OVERVIEW OF MEASUREMENT SYSTEMS ANALYSIS (MSA)A Measurement System is the combination of people, equipment, materials, methods, environme
16、nt, analysis and decisions made on the measured results. All measurement systems have a level of uncertainty associated with them because of variation in these factors. MSA is the method of identifying the level of uncertainty of the whole system so that we can determine if the Measurement system is
17、 fit for its intended purpose, i.e., the level of measurement variation is not significant (Table 2 shows the acceptance limits for MSA).There are several types of MSA; which type is required will depend on the type of data being measured and the influences on the system (see Figure 2).The purpose o
18、f MSA is to identify the total variation present in the system so that actions can be taken to effectively control it and ensure repeatable and accurate measurements. These studies should be conducted to represent the real world as much as possible; e.g., range of inspectors, parts that cover the wh
19、ole specification, normal working environment, etc.MSA shall be conducted as part of New Product Introduction to validate the measurement system prior to production. There are also situations where MSA should be repeated, these include: changes to gauge design, refurbishment/repair, environment, pro
20、duct design change to the feature being measured, etc.SAE INTERNATIONAL AS13003 Page 6 of 45Table 1 describes situations where MSA is required. Note that in this context MSA refers to the methods described in Table 2. Which tests are applicable will depend on the type of data being measured and the
21、influences on the system (see Figure 2).This standard defines the minimum acceptance limits for MSA and provides guidance for most situations but there may be situations where alternative methods are required. In such cases they must be approved by the purchaser.Table 1 - MSA applicationsEvent Event
22、 Description Action1 New inspection device or method introduction. Perform MSA 2 New/Changed Production Process.Evaluate current or Perform MSA3Any significant change to the current inspection device or method:i.e., equipment, operator, environment, location, sequence, calibration standard, Inspecti
23、on house, CMM software or hardware changeEvaluate current or Perform MSA 4Following a product escape related to (or suspected to be) from the Measurement System (nonconforming material left the facility).Evaluate current or Perform MSA5Change in how an inspection device or method is used, or its app
24、lication*.For example:1. When changing from simple geometry to complex. Moving from simple linear dimensions with flat parallel surfaces to non-flat (non-parallel) surfaces with geometric constructions required.2. When changing from similar to non-similar product characteristics. Moving from visual
25、inspection of edge breaks with dimensional requirements to visual inspection of cosmetic appearance requirements.Perform MSA6 Product requirements are changed to be more restrictive or tightened.Recalculate from base data or Perform MSA7As part of a First Article Inspection (FAI) following a lapse i
26、n use of more than 24 months.Evaluate current MSA8Existing inspection device or method is being used to accept product and has not previously been evaluated per this standard as directed by purchaser.Perform MSA where required 9Product audit non-conformance or product investigation when suspected to
27、 be from the measurement system.Evaluate current or Perform MSA10 To verify a measurement system is adequate before SPC.Perform MSA where required * Different product with similar geometry and tolerances are typically not considered a change in application. NOTES:x Specifications within this table a
28、pply unless otherwise stated by the purchaser x The term “evaluate” means a confirmation that the MSA study characteristics are still valid and additional measurement uncertainty has not been inducedSAE INTERNATIONAL AS13003 Page 7 of 455. ORGANIZATION AND COMPETENCE REQUIREMENTSThe correct training
29、 of MSA practitioners is key to the successful outcome of the process. Each supplier shall employ or have access to a practitioner who has appropriate experience and can demonstrate competence that includes all elements of this standard. It is expected that the practitioner will periodically confirm
30、 compliance to the standard. Individuals involved in the study must be suitably trained and competent in the measurement task. They must be representative of the measurement system users (see 8.1.3). The MSA study must be lead or facilitated by a person trained and competent in the methodology cover
31、ed in this standard.The supplier shall nominate a suitably qualified and experienced person from within their own organization as accountable for deployment of this standard and respective compliance.6. QUALITY SYSTEMx The supplier shall have a documented process within its own quality system which
32、meets the requirements of this standard. The process shall be fully implemented and subject to an audit.x The documented MSA process shall describe the training and competency requirements for practitioners of this process.x Records of MSA studies identifying measurement systems as capable shall be
33、maintained within the organizationsquality system and subject to the same level of record retention as its FAI Records.7. MEASUREMENT SYSTEMS ANALYSIS REQUIREMENTS7.1 Pre-RequisitesThe pre-requisites and generic requirements for any type of MSA study are:x The measurement equipment must be calibrate
34、d and traceable to a relevant national or international standard.x The measurement equipment must be maintained in good condition and checked for evidence of damage or wear, which may impact the measurement capability.x Production parts must be used for studies, except for circumstances where the us
35、e of representative parts or artefacts is authorized (see 8.1.1 and 8.1.2). The parts must represent the full tolerance and it is beneficial to include parts just outside the LSL and USL.x The parts should be as clean and burr free as would be seen by the production inspection method.x Individuals i
36、nvolved in the study must be suitably trained and competent in the measurement task. They must be representative of the measurement system users (see 8.1.3).x The measurement system analysis study must be lead or facilitated by a person trained and competent in the methodology covered in this standa
37、rd.x An environment representative of the production operation must be used for the MSA study.x The method used for any study must replicate the conditions in the production process. Where alignment, fixturing,and clamping could influence the measured value, the component must be removed and reloade
38、d between each measurement. Deviation from this requires purchaser authorization.x During the study, the personnel performing the measurements must not have visibility of either their own or other study participants previous results.SAE INTERNATIONAL AS13003 Page 8 of 457.2 Considerations when Plann
39、ing a MSA StudyMSA Studies require careful planning to ensure that the results are truly representative of the measurement system. The system shall be fully evaluated to identify what could affect the results so that anything likely to contribute to the variation is included in the study. An MSA is
40、essentially an experiment to determine the degree and causes of variation within a measurement system. As such, careful use of Design of Experiments is recommended. See also 8.1.Factors that need to be evaluated include:x Environment temperature, humidity, contamination, vibration, electromagnetic r
41、adiation, etc.x Location different buildings, sites, etc.x Part variation that will affect the measured value (surface finish, flexibility, shape, size, etc.) x People shift patterns, times of the day, experience levelsx Process fixtures, probes, accessories, etc.A useful way of visually expressing
42、the factors is to use a tree diagram example shown below.SAE INTERNATIONAL AS13003 Page 9 of 45Figure 1 - Planning an MSA studySAE INTERNATIONAL AS13003 Page 10 of 45Figure 2 - Selecting the appropriate measurement systems analysis methodsFigure 2 shows methods of assessing MSA that can be applied i
43、n a logical order. The selection of methods should be based on purchaser requirements (i.e., not all tests may be required). The type of measurement being conducted and the study characteristics such as part availability, number of operators, number of repeat measurements, etc., many influence the s
44、election of one method over another. The detailed descriptions and case studies within this standard can guide the user to the selection of MSA methods. See 7.2 of this standard.SAE INTERNATIONAL AS13003 Page 11 of 457.3 MSA Minimum RequirementsTable 2 - Minimum requirements for MSA* Repeatability a
45、nd Gauge R e.g., left and right handed people, different levels of eyesight acuity, height, strength, etc.All participants in the measurement study shall be trained and experienced in the task. Do not include people who do not normally carry out the measurement activities as part of their day-to-day
46、 duties. Do not include experts like Metrologists or Manufacturing Engineers unless they are representative of typical users.8.1.4 Low Sample SizesIdeally at least ten parts or features should be available for the measurement study. Using three operators measuring each part a minimum of two (2) time
47、s would give sixty data points, which is sufficient to give meaningful result.Sometimes though there may not be sufficient parts available. There are a number of ways that this problem can be overcome:x Conduct the study over a longer period of time as parts become available. This also has the advan
48、tage of incorporating any time based factors into the study.x Use multiple features on one (1) part. For example, a slotted disc may contain several identical features which can be identified and used to conduct the study. Potential problems with using this method include randomizing the measurement
49、s effectively and a lack of variation in the features, but with care this can be accomplished. Be aware that this method may exclude sources of variation that could be affecting the measurement values and any results obtained may not be fully representative.x Use scrap parts. So long as the part is representative of a finished part (all features are present and the geometry and surface finish are correct) t
